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Melting fuse and no tail lights or dash lights

Cheetokps

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Hello, I am having an issue where every now and then my tail lights, dashboard lights, and side markers will turn off. Often it will go back to normal or I can wiggle around the fuse and it will fix it. However, this time I was not able to fix it and had to drive 2 hours on the highway with no tail lights. I fixed it briefly, but I slammed my door and they shut off again and I couldn't get it back. I replaced all the fuses but it did not help.

Also when I wiggle the fuse around (the top right on, for parking lamps- fuse 1) it feels "crunchy" and I can see sparks in there. Plus when I take the fuse out it is HOT and burns my hand, and a few fuses have had the plastic melt on them from the heat. I am wondering if something is stuck inside the fuse box or something? If so would I just have to replace the fuse box, or take it apart, if possible?

The burning fuse worries me, and also driving at night without tail lights seems dangerous so this is something I would really like to fix
 

Kraken72

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You have a bad connection or broken wiring that you need to fix. look behind the fuse that keeps blowing to see what is going on. Also disconnect your battery for safety. I just had a bad connection in my pdc that prevented my Jeep from starting.
 

flyinfish

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I'd be very concerned about the arcing and the heat that it causes. Fire is the next stop.
It appears like the terminals on the back side of the fuse block are coming in contact with each other and causing a direct short.

First, disconnect the battery!
You should inspect the fuse slot empty and look for a foreign object and then I'd remove the screws from the fuse block and carefully roll it over to see the back side. There fuse block may have a broken area on back that is allowing the short. You may end up needing to replace the fuse block but you need to find out what is causing the issue. My guess is it will obvious once you see the backside.
 
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Jerry Bransford

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I'd remove the covers off all the external lights and check the bulb sockets plus the wiring leading to them. Verify each bulb is inserted correctly and wasn't accidentally installed 180 backwards which can happen with the tail/brake light bulbs. That by itself can cause a short and problem.
 

mrblaine

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I'd remove the covers off all the external lights and check the bulb sockets plus the wiring leading to them. Verify each bulb is inserted correctly and wasn't accidentally installed 180 backwards which can happen with the tail/brake light bulbs. That by itself can cause a short and problem.

To clarify, only the stop/turn 1157 can be put in backwards due to having 2 contacts and offset pins on the side.
1655299438671.png

The single contact 1156 has same height pins that are not offset and a single contact on the bottom so it can go into the socket either way.

1655299529690.png
 
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Cheetokps

Cheetokps

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I'd remove the covers off all the external lights and check the bulb sockets plus the wiring leading to them. Verify each bulb is inserted correctly and wasn't accidentally installed 180 backwards which can happen with the tail/brake light bulbs. That by itself can cause a short and problem.

I think what @flyinfish said might be right because it feels like a foreign object is in there when I put the fuse in, but thanks I’ll definitely try that if I don’t find anything
 
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Cheetokps

Cheetokps

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I'd be very concerned about the arching and the heat that it causes. Fire is the next stop.
It appears like the terminals on the back side of the fuse block are coming in contact with each other and causing a direct short.

First, disconnect the battery!
You should inspect the fuse slot empty and look for a foreign object and then I'd remove the screws from the fuse block and carefully roll it over to see the back side. There fuse block may have a broken area on back that is allowing the short. You may end up needing to replace the fuse block but you need to find out what is causing the issue. My guess is it will obvious once you see the backside.
Thanks, I wasn’t sure how to get to the back side or if I even could. I’ll definitely try this tonight, I was very nervous driving home about fire

It’s been doing this for a while tbh, but usually I can wiggle it around and the lights turn back on. I should have fixed it sooner but I won’t waste any more time
 
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Cheetokps

Cheetokps

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The previous owner had already installed one of those add-a-fuse tape things underneath one of the other 20a fuses, so I’m wondering if there was one on this fuse that broke off inside or something possibly? This isn’t the only sketchy wiring I’ve seen in here, all the wiring behind the head unit is shitty too
 
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flyinfish

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Thanks, I wasn’t sure how to get to the back side or if I even could. I’ll definitely try this tonight, I was very nervous driving home about fire

It’s been doing this for a while tbh, but usually I can wiggle it around and the lights turn back on. I should have fixed it sooner but I won’t waste any more time

Just for clarity, I understood your original post to say that the fuse itself doesn't blow but gets hot enough to melt the plastic body of fuse. If the fused circuit was shorted, it should blow that fuse immediately. That is why I presume there's a short on the hot terminal side to something nearby.
 
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Cheetokps

Cheetokps

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Just for clarity, I understood your original post to say that the fuse itself doesn't blow but gets hot enough to melt the plastic body of fuse. If the fused circuit was shorted, it should blow that fuse immediately. That is why I presume there's a short on the hot terminal side to something nearby.

Yeah none of the fuses have blown, I keep checking with different fuses and it doesn’t help. I have those fuses that glow when they blow too but not sure if it even works

It seems like the right side prong of the fuse in particular gets really hot and melts the plastic a bit. I think the brake light fuse was also meting a bit, but they still work
 

hear

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Just for clarity, I understood your original post to say that the fuse itself doesn't blow but gets hot enough to melt the plastic body of fuse. If the fused circuit was shorted, it should blow that fuse immediately. That is why I presume there's a short on the hot terminal side to something nearby.

I would be concerned that the fuse isn't the right size for the circuit. I had some "excess heat" as a result of a short combined with a 20A fuse on a circuit that could only carry 10A. Enough heat to melt the plastic on the fuse is a problem just waiting to become a "so my TJ burned to the ground today" post.
 

flyinfish

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I would be concerned that the fuse isn't the right size for the circuit. I had some "excess heat" as a result of a short combined with a 20A fuse on a circuit that could only carry 10A. Enough heat to melt the plastic on the fuse is a problem just waiting to become a "so my TJ burned to the ground today" post.

The circuit the op is having issues with is a 20A circuit.

You mean I can't just put a bigger fuse in until it stops blowing or the wire burns up. :LOL:
Sadly, there are some that think when a fuse blows, get a higher amp fuse.
 
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flyinfish

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Yeah none of the fuses have blown, I keep checking with different fuses and it doesn’t help. I have those fuses that glow when they blow too but not sure if it even works

It seems like the right side prong of the fuse in particular gets really hot and melts the plastic a bit. I think the brake light fuse was also meting a bit, but they still work

Since there's arcing local to that area and when you wiggle the fuse, that's a big clue that something is a miss in the upper right hand corner of fuse block. I'd inspect the back side of the fuse block very closely around both of those 20A circuits.
 

sab

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A couple points:
  1. Arcing from a bad connection generates heat, and with a 20A circuit, that can be significant heat.
  2. A bad connection could be at the crimp of the terminal to the wire, but it can also be between the spade on the fuse and the contacts of the terminal.
The first think I'd look for is the terminal being relaxed and not engaging the fuse spade with enough interference. Those terminals are pretty fragile, and rough-handling with fuse replacement (debris between the contacts can do the same thing) can spread the contacts and make for a loose fit, which you may or may not feel. If both terminals for that fuse are spread, you'd feel reduced force when installing the fuse, but if only one side is loose, you may not feel it. If this is the problem, you can bend the contacts together with a jeweler's screwdriver to get good contact with the fuse again. Edited to add: Disconnect the battery before you attempt to bend the terminal contacts!
 
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Cheetokps

Cheetokps

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image.jpg

So first thing I notice, shouldn’t there be a wire going behind the location of the “STOP LPS (20A)” fuse which I’m assuming is brake lights?

1C670191-A82C-43CB-8145-8D579CC3252C.jpeg
 
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Cheetokps

Cheetokps

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A couple points:
  1. Arcing from a bad connection generates heat, and with a 20A circuit, that can be significant heat.
  2. A bad connection could be at the crimp of the terminal to the wire, but it can also be between the spade on the fuse and the contacts of the terminal.
The first think I'd look for is the terminal being relaxed and not engaging the fuse spade with enough interference. Those terminals are pretty fragile, and rough-handling with fuse replacement (debris between the contacts can do the same thing) can spread the contacts and make for a loose fit, which you may or may not feel. If both terminals for that fuse are spread, you'd feel reduced force when installing the fuse, but if only one side is loose, you may not feel it. If this is the problem, you can bend the contacts together with a jeweler's screwdriver to get good contact with the fuse again. Edited to add: Disconnect the battery before you attempt to bend the terminal contacts!

I think you’re right, the right side (where it’s burning) looks like it has a big gap
image.jpg
 

flyinfish

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I think you’re right, the right side (where it’s burning) looks like it has a big gap
View attachment 337334

That would be an issue, look at how the terminals are wide and scorched.

The previous photo looks like back is good.
I haven't looked at a schematic for your year but they must have a strap between the stop and park which is why the park lights wire looks to be 10Ga.
 
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sab

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So first thing I notice, shouldn’t there be a wire going behind the location of the “STOP LPS (20A)” fuse which I’m assuming is brake lights?

It's likely internally bussed.
 
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Cheetokps

Cheetokps

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Yes, thank you guys the side markers and tail lights work now. Just had to bend the terminal contact.

But I might not be done… my dash lights aren’t coming on still. I know they’re dim so I covered the dash with a sweatshirt to block out light and they’re definitely not coming on. Also I hear a buzzing noise only when the lights are switched on/the fuse is in… any ideas?

Maybe the bulb blew because of this too or something?
 
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